Observations (1)
I have observed a serious decline in the diversity and populations of invertebrates, particularly in the last five years; I am in no doubt about this. There is much in the news these days about the decline in pollinating insects and the potential dangers of such reductions to certain food supplies and this is being attributed to the use of a new generation of pesticides known as neonicotinoids which were banned in the European Union in 2018.
The ongoing effect of these once used pesticides may be a contributory factor to the declining populations of invertebrates on the common but it cannot be the sole reason as there is no arable farmland on the Common or within close proximity where such pesticides would have been used so one has to ask “What has changed on the Common that might have the effect of severely reducng the invertebrate populations?”
I repeat that I can only suggest possible causes but I have no evidence or data to support my theories nor am I party to other points of view. I have no qualifications, I am just an enthusiastic nature lover so please excuse my passion and my desire to see both the ecology and the economics of the Common succeed.
The changes that have occurred on the Common in recent times that may have contributed to the problem may be:
The designation of the SSSI purely on the basis of ‘interesting plant communities in a scarce habitat type’.
Excessive scrub clearance beyond that needed to comply with Natural England’s “view about management” for the site.
The density of grazing during the summer months
The use of antibiotics in cattle to prevent rather than cure certain conditions
Radical changes from the ancient management of the common but still complying with its basic purpose, the grazing of commoners livestock
Some pollution of the site during essential works on power lines crossing the common and on the railway bridge
No active management of winter flood levels
Clearly this is all complex stuff and I will expand on them in the coming posts
Observations (2)
One possible reason for the decline in invertebrates on the Common could stem from the fact that the common was designated a SSSI because it is scarce flood grazing pasture and has some interesting plant communities. It may seem odd suggesting that designation as a SSSI could be having an adverse effect on the Common’s ecology but bear with me while I try to explain.
The 2010 survey by Natural England described the interesting plants present, it made no mention of invertebrates or vertebrate life. The resulting report expressed concerns that the plant communities in some of the ditches were deteriorating due to scrub growth on the northern side of some of these ditches.
The Natural England view about management says “An element of managed scrub, both within and fringing a field can be of importance to birds and invertebrates, as can a surrounding hedge.” The principle here is that some sensitive management of scrub on the north side of ditches was required but that some scrub should be left for the benefit of birds and invertebrates.
In recent years almost all of the scrub has been removed and not just from the designated SSSI sections. In the first stage the clearings were burnt shrouding Carey in bonfire smoke for an hour or so! The second stage, fortunately, did not involve burning and the scrub was left in piles so that any insect larvae had time to emerge. It also forms some useful cover for the large house sparrow and starling flocks on the northern edge of the Common.
This scrub removal would not appear to have been sensitively done but appears to be somewhat indiscriminate and perhaps over zealous? I do not know whether this was done as a result of direction from Natural England or whether someone decided that if the scrub had to go then let’s get rid of all of it.
Whatever the reason, the scrub was mainly bramble and so many of the bramble flowers for pollinators and resulting blackberries for autumn creatures have gone. The habitat for insects to lay eggs and for their larvae to feed has been destroyed and the web sites for many spiders has gone, so too has the potential nesting cover for some smaller species of birds; stonechat for example
The management plan for the Common is designed to protect interesting plant communities but has its implementation severely damaged the overall ecology of the Common?
Observations (3)
Wareham Common was established many centuries ago so that local ‘commoners’ could run their cattle on it for the benefit of the local community providing both dairy produce and meat for the townsfolk. The flood grazing marsh habitat we see today is a result of that practice over hundreds of years.
In their view about management for the common Natural England say “Traditionally, this management is achieved by grazing. Cattle are often the preferred stock, being relatively tolerant of wet conditions and able to control tall grasses and rank vegetation. Cattle also tend to produce a rather uneven, structurally diverse sward.” The presence of grazing livestock is essential to the wellbeing of the common’s nature.
However, the Natural England view on management goes on to say that “Grazing usually takes place at times between late spring and early autumn, but the precise timing and intensity will depend on local conditions and requirements, such as the need to avoid trampling ground-nesting birds. Heavy poaching should be avoided but light trampling can be beneficial in breaking down leaf litter and providing areas for seed germination.”
It would be wrong to think that the grazing as we see it today and the breed of cattle on the Common has remained unchanged since medieval times. The Court Leet paper I referred to suggests there were 30 ‘runs’ on the common and I take that to mean 30 animals made up of either cattle or horses.
The cows on the common these days are Holstein Friesians which were first brought to Britain after the second world war but they have only been widely used for dairy purposes since the 1970’s; they are far from a traditional breed and have been bred to eat lots of grass so as to produce lots of milk per animal.
The DERFRA website suggests that 1.5 cattle per hectare is a reasonable density of grazing for most breeds of cattle. Wareham Common is about 32 hectares which would suggest 48 cattle is the maximum the common can support however not all of the Common is now suitable for grazing; the land between the railway and the road for example. This would reduce the advisable number of cattle to around 40 and, although I have never thought to count them, I would suggest that is probably the number on the common in current times; it is certainly in excess of 30 runs.
The 1.5 cows per hectare assumes that the cattle are free to roam unimpeded over the whole area and so make their way leisurely around choosing the best grass to feed on. The Common is, however, segmented by the railway/road and the river and so I reckon there are five individual segments and the 40+ cattle are moved every few days between them in rotation. If all the segments were the same size then each would only support 8 cattle not 40. I would have to ask whether the result is heavy poaching which should be avoided?
This is something of a conundrum; the Common needs to be grazed but the farmer needs a minimum number of cows to make grazing viable. If the economic number of cattle exceeds the number best for environmental control the issue is irreconcilable as to insist on a reduction in the number of cattle would lead to no cattle at all and so the environment of the Common suffers both ways!
Observations (4)
I think there may be another reason why cattle grazing is potentially having an adverse effect on biodiversity on the Common.
I am venturing into the realms of veterinary science here which I am reluctant to do with no background in this particular field but it seems that cattle are now fed antibiotics as a preventative measure rather than as a remedy. A farming website says “There is a widely held and justifiable belief, by both medics and vets, that controlled intervention to prevent the outbreak and further spread of disease in infected or carrier animals, based on sound professional examination and advice, is better than cure.”
I have no idea if the cattle on the Common are receiving this treatment but one thing I have noticed since this practice came into being around five years ago is that the good old fashioned ‘country pancake’ we were familiar with has all but gone. Cow excrement is now slimy and smeared across the grass and can be unpleasant to negotiate on foot.
That is not my main concern however. When a new ‘pancake’ was deposited an abundance of flies, yellow dung fly and greenbottle in particular, and species of scarab beetles would descend on it to lay eggs. Their eggs hatch into larvae which eat the cow pat thus naturally biodegrading it. It seems nothing can deal with the new form of excrement partly because it contains antibiotics that kill the emerging larvae.
The flies that used cow pats had benefits to human beings and the environment other than just decomposing and freeing us from cow dung, they contributed to the pollination of some plants and are food for some other animals, mainly birds. Yellow dung flies now seem scarce on the common.
Whilst this practice may be good for the farmer it may prove not to be so for those who like a sirloin steak as the NHS point out that it seems to be driving up antibiotic resistance in humans leading to new superbugs; Covid 19 perhaps?
Wareham Common is designated as nationally scarce grazing flood marsh habitat and that is part of the reason it has been designated as a Site of Special Scientific Interest; the marsh has been grazed by stock for centuries and the level of flooding has been controlled to ensure flooding occurs but also to ensure that is not too excess.
I have outlined a couple of observations about the degree of grazing that occurs now but I also worry about the level of flooding over the last few winters. The recent winters have been mild and very wet and the eastern block of the SSSI nearest the town this winter seemed to be a large lake from mid-December until the end of March and extended periods of flooding seem to be the norm now. I have only been here fifteen years and I have not kept precise records but I am pretty certain this is something that is getting worse as changes to our climate change the nature of our winters. There are predictions of course that this could get worse if action to reduce CO2 content in the atmosphere are not stabilised and then reduced.
Whilst controlled flooding was used to good effect I can’t help but conclude that extended flooding is not good for any form of animal life, be that mammal, reptile, bird or insect. It is certainly many years since lapwing were a regular sight on the common although numbers of lapwing have fallen dramatically internationally and so extended flooding is probably not the only reason for their loss.
With the current situation there can be little prospect of bird populations on the Common improving and yet coastal flood grazing as a habitat type is recognised as being important for wintering and breeding wildfowl and waders.
The Natural England view about management makes no mention of flooding control and the maintenance of habitat for animal life, it seems that only the interesting plant communities in the ditches are worthy of protection.
Being new around here I have no idea who, if anyone, is responsible for controlling flood levels in the way this was done in the past. I do not know if it is possible to exercise control over the degree of flooding given the wet climate we now have. If flooding can still be controlled, was it a calculated decision to abandon that control or has the practice just fallen by the wayside?
Whatever the reason, what is happening to the flooding of the Common now surely cannot be good for its ecology of the common?C
The potential for rising sea levels could aggravate the situation even more in years to come given the Common is only a couple of metres above mean tide levels in places and even a small rise could see the area become tidal and saline. If that happens Natural England can say goodbye to the ‘interesting plant communities’ they seek to protect.
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